1. Field of the Invention
This invention relates to wheel end assemblies and, in particular, to a wheel end assembly designed to allow venting of excess pressure from a hubcap while protecting against entry of foreign objects and elements.
2. Discussion of Related Art
A conventional wheel end assembly includes a hubcap that is coupled to a vehicle wheel and covers the end of an axle spindle and the wheel bearings upon which the wheel is rotatably mounted. The hubcap provides a reservoir for lubricants for the wheel bearings and also protects the wheel bearings from contaminants. As the temperatures of the wheel bearings rise, the pressure within the chamber defined by the hubcap also rises. Accordingly, a conventional wheel end assembly generally includes means for venting pressurized fluid from the chamber. One conventional venting means comprises an elastomeric plug as shown in any of U.S. Pat. Nos. 5,482,358, 5,752,746, and 5,860,708. The use of an elastomeric plug to vent internal pressure, however, can allow entry of contaminants into the hubcap chamber (e.g., water used during high pressure washing). Accordingly, wheel end assemblies have been developed that incorporate caps that cover the plug outlet and that attempt to both direct the vented pressure and protect the plug from exposure to contaminants as described in the U.S. Pat. Nos. 5,752,746 and 5,860,708.
The above-described wheel end assemblies still have significant drawbacks. The structure for the cap typically includes numerous pieces and are relatively complex. Further, the cap is typically mounted directly to the hubcap or wheel thereby making removal and/or maintenance of the cap and plug difficult.
The inventors herein have recognized a need for a wheel end assembly that will minimize and/or eliminate one or more of the above-identified deficiencies.
The present invention provides an improved wheel end assembly.
A wheel end assembly in accordance with the present invention includes a hubcap that is configured for coupling to a wheel and that defines a chamber that retains lubricant for wheel bearings for the wheel. A wall of the hubcap has an aperture that is in fluid communication with the chamber. A plug is disposed within the aperture and extends in an outboard direction from the wall of the hubcap. The plug has a body and defines a valve for releasing pressurized fluid from the chamber. The assembly also includes a cap that is supported on the body of the plug and extends in an outboard direction therefrom. The cap is disposed over an outlet of the valve and defines a fluid chamber in fluid communication with the outlet and ambient air.
A wheel end assembly in accordance with the present invention is advantageous. First, the design of the cap is less complex than conventional caps and does not require filters or other inserts. Accordingly, a wheel end assembly in accordance with the present invention is less expensive than conventional wheel end assemblies. Second, because the cap is supported on the plug rather than fastened to the hubcap or wheel, the cap and plug are much easier to install and to remove from the assembly during maintenance as compared to conventional wheel end assemblies. Finally, in accordance with one embodiment of the invention, the cap and plug can be removed as a unit from the assembly.
These and other advantages of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.